The link in

"refer to the example applications"

at

http://doc.qt.io/qt-5/qserialport.html

goes to

http://doc.qt.io/qt-5/qdir.html#examples

It should go to

http://doc.qt.io/qt-5/qtserialport-examples.html

I'm not sure how it points wrong, but it might be a matter of changing the link target in the \l from Examples to Qt Serial Port Examples. Not sure though.